cmd: add exception command

The 'exception' command allows to test exception handling.

This implementation supports ARM, x86, RISC-V and the following exceptions:
* 'breakpoint' - prefetch abort exception (ARM 32bit only)
* 'unaligned'  - data abort exception (ARM only)
* 'undefined'  - undefined instruction exception

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

3 files changed, 101 insertions, 0 deletions

diff --git a/cmd/arm/Makefile b/cmd/arm/Makefile
new file mode 100644
index 0000000000..94367dcb45
--- /dev/null
+++ b/cmd/arm/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+ifdef CONFIG_ARM64
+obj-$(CONFIG_CMD_EXCEPTION) += exception64.o
+else
+obj-$(CONFIG_CMD_EXCEPTION) += exception.o
+endif
diff --git a/cmd/arm/exception.c b/cmd/arm/exception.c
new file mode 100644
index 0000000000..33bc75976f
--- /dev/null
+++ b/cmd/arm/exception.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'exception' command can be used for testing exception handling.
+ *
+ * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_unaligned(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	/*
+	 * The LDRD instruction requires the data source to be four byte aligned
+	 * even if strict alignment fault checking is disabled in the system
+	 * control register.
+	 */
+	asm volatile (
+		"MOV r5, sp\n"
+		"ADD r5, #1\n"
+		"LDRD r6, r7, [r5]\n");
+	return CMD_RET_FAILURE;
+}
+
+static int do_breakpoint(cmd_tbl_t *cmdtp, int flag, int argc,
+			 char * const argv[])
+{
+	asm volatile ("BKPT #123\n");
+	return CMD_RET_FAILURE;
+}
+
+static int do_undefined(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	/*
+	 * 0xe7f...f.	is undefined in ARM mode
+	 * 0xde..	is undefined in Thumb mode
+	 */
+	asm volatile (".word 0xe7f7defb\n");
+	return CMD_RET_FAILURE;
+}
+
+static cmd_tbl_t cmd_sub[] = {
+	U_BOOT_CMD_MKENT(breakpoint, CONFIG_SYS_MAXARGS, 1, do_breakpoint,
+			 "", ""),
+	U_BOOT_CMD_MKENT(unaligned, CONFIG_SYS_MAXARGS, 1, do_unaligned,
+			 "", ""),
+	U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
+			 "", ""),
+};
+
+static char exception_help_text[] =
+	"<ex>\n"
+	"  The following exceptions are available:\n"
+	"  breakpoint - prefetch abort\n"
+	"  unaligned  - data abort\n"
+	"  undefined  - undefined instruction\n"
+	;
+
+#include <exception.h>
diff --git a/cmd/arm/exception64.c b/cmd/arm/exception64.c
new file mode 100644
index 0000000000..a363818532
--- /dev/null
+++ b/cmd/arm/exception64.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'exception' command can be used for testing exception handling.
+ *
+ * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_undefined(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	/*
+	 * 0xe7f...f.	is undefined in ARM mode
+	 * 0xde..	is undefined in Thumb mode
+	 */
+	asm volatile (".word 0xe7f7defb\n");
+	return CMD_RET_FAILURE;
+}
+
+static cmd_tbl_t cmd_sub[] = {
+	U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
+			 "", ""),
+};
+
+static char exception_help_text[] =
+	"<ex>\n"
+	"  The following exceptions are available:\n"
+	"  undefined  - undefined instruction\n"
+	;
+
+#include <exception.h>